Indonesia produces more marine plastic pollution than any other country except China. This is perhaps unsurprising: the world’s biggest archipelago is also its fourth most populous. Limited income and cash flow means that poorer communities rely on cheap single-use plastics like bags, water cups and shampoo sachets. Waste management systems are rudimentary and each year millions of tonnes of trash ends up in waterways and eventually the ocean.

Last year Indonesia pledged US$1 billion to cut its marine waste by 70% by 2025. The country will have to tackle the issue on multiple fronts if this ambitious target is to be met. Besides changing consumer habits and improving waste management infrastructure, industry needs to move away from single use plastics and quickly introduce and scale up biodegradable alternatives.

This is where seaweed comes in. Indonesia’s seaweed production is second only to China and is increasing by an estimated 30% a year. Indonesia is also the world’s biggest producer of red seaweed, a variety that’s ideal for creating bio-plastics and packaging.

Currently, most bio-plastics derive from terrestrial sources related to the food industry, including corn, sugarcane and cassava. However, according to Bakti Berlyanto Sedayu, a researcher with the Indonesian Ministry of Marine Affairs and Fisheries, seaweed is a far more sustainable alternative.

Sedayu says that land based bio-plastics require huge investments in land, risking the kind of catastrophic deforestation we’re seeing with palm oil. They also use fertilizers and pesticides and are not always as biodegradable as they’re touted to be.

By contrast, seaweed is cheap to produce as it is cultivated offshore, grows quickly and doesn’t require fresh water or chemicals to grow successfully. Seaweed beds are also natural carbon sinks, de-acidifying water.

An Indonesian woman harvests seaweed at her farm off the beach in Nusa Dua, Bali, Indonesia. Photograph: Ed Wray/AP

Conditions in Indonesia are ideal for seaweed farming - the sun shines more or less year round and there are more than 34,000 miles of coastline. And as pressure on fish stocks continues to increase, coastal populations are turning to aquaculture as an alternative. Sedayu believes it could take just five to ten years to bring the production of bio-plastics up to an industrial scale - though this would require careful management.

For now, seaweed based packaging is barely in its infancy. Indonesian start up Evoware is producing seaweed products that are edible, including jelly glasses, sachets and food wrapping. But they are produced by hand and are only available for companies to sample as part of their testing phase. This will soon change however according to founder and CEO David Christian.

“We’re expecting to be fully automated by next year,” the 23-year-old entrepreneur explains. “When that happens, our edible packaging will cost around 30% more than existing plastics, which is competitive.”

Evoware also work directly with seaweed growers. Right now, 80% of seaweed is processed outside Indonesia and the lengthy supply chains mean that farmers see a small fraction of the profit. “We teach them how to grow high quality seaweed and to wash it properly, plus we pay double the price they’d normally get,” says Christian.

Companies and consumers will need to change their practices if seaweed based packaging and bio-plastics are to have any hope of going mainstream. There are encouraging signs that there is nascent political will to create this shift. Earlier this month, the Indonesian government teamed up with the country’s two biggest Islamic organisations to encourage their followers - more than 200 million of them - to cut out single use plastics.

Citizen movements like the Bye Bye Plastic Bags campaign in Bali - a local project led by schoolchildren that has gone global - have helped put the issue of plastic waste in the spotlight. For the last three years, the annual Coral Triangle Day celebrations, which fall on June 09 after World Ocean’s Day, have included a social media contest to encourage consumers to reconsider their relationship with single-use plastics.

Having signed up to the UN Clean Seas campaign, which is targeting both production and consumption of single-use plastic, the Indonesian government will now need to develop legal frameworks at national and regional levels to provide a foundation for new supply chains, effective waste management and community engagement. Pledges need now to be backed by concerted, concrete action.